Java tutorial
/* * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* * XStream.java * Copyright (C) 2008-2012 University of Waikato, Hamilton, New Zealand */ package weka.core.xml; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import java.io.Reader; import java.io.Writer; import weka.core.RevisionHandler; import weka.core.RevisionUtils; /** * This class is a helper class for XML serialization using <a * href="http://xstream.codehaus.org" target="_blank">XStream</a> . XStream does * not need to be present, since the class-calls are done generically via * Reflection. * * @author Mark Hall (mhall{[at]}pentaho{[dot]}org) * @version $Revision$ */ public class XStream implements RevisionHandler { /** * indicates whether <a href="http://xstream.codehaus.org" * target="_blank">XStream</a> is present */ protected static boolean m_Present = false; /** the extension for XStream files (including '.') */ public final static String FILE_EXTENSION = ".xstream"; /** check for XStream statically (needs only to be done once) */ static { checkForXStream(); } /** * checks whether the XStream is present in the class path */ private static void checkForXStream() { try { Class.forName("com.thoughtworks.xstream.XStream"); m_Present = true; } catch (Exception e) { m_Present = false; } } /** * returns whether XStream is present or not, i.e. whether the classes are in * the classpath or not * * @return whether XStream is available */ public static boolean isPresent() { return m_Present; } /** * Serializes the supplied object xml * * @param toSerialize the object to serialize * @return the serialized object as an XML string * @throws Exception if something goes wrong */ public static String serialize(Object toSerialize) throws Exception { Class<?> xstreamClass; java.lang.reflect.Constructor<?> constructor; Object xstream; Class<?>[] serializeArgsClasses = new Class[1]; Object[] serializeArgs = new Object[1]; java.lang.reflect.Method methodSerialize; String result; xstreamClass = Class.forName("com.thoughtworks.xstream.XStream"); constructor = xstreamClass.getConstructor(); xstream = constructor.newInstance(); serializeArgsClasses[0] = Object.class; serializeArgs[0] = toSerialize; methodSerialize = xstreamClass.getMethod("toXML", serializeArgsClasses); // execute it try { result = (String) methodSerialize.invoke(xstream, serializeArgs); } catch (Exception ex) { result = null; } return result; } /** * writes the XML-serialized object to the given file * * @param filename the file to serialize the object to * @param o the object to write to the file * @return whether writing was successful or not * @throws Exception if something goes wrong while writing to the file */ public static boolean write(String filename, Object o) throws Exception { return write(new File(filename), o); } /** * write the XML-serialized object to the given file * * @param file the file to serialize the object to * @param o the object to write to the file * @return whether writing was successful or not * @throws Exception if something goes wrong while writing to the file */ public static boolean write(File file, Object o) throws Exception { return write(new BufferedOutputStream(new FileOutputStream(file)), o); } /** * writes the XML-serialized object to the given output stream * * @param stream the output stream * @param o the object to write * @return true if everything goes ok */ public static boolean write(OutputStream stream, Object o) throws Exception { Class<?> xstreamClass; java.lang.reflect.Constructor<?> constructor; Object xstream; Class<?>[] serializeArgsClasses = new Class[2]; Object[] serializeArgs = new Object[2]; java.lang.reflect.Method methodSerialize; boolean result = false; xstreamClass = Class.forName("com.thoughtworks.xstream.XStream"); constructor = xstreamClass.getConstructor(); xstream = constructor.newInstance(); serializeArgsClasses[0] = Object.class; serializeArgsClasses[1] = OutputStream.class; serializeArgs[0] = o; serializeArgs[1] = stream; methodSerialize = xstreamClass.getMethod("toXML", serializeArgsClasses); // execute it try { methodSerialize.invoke(xstream, serializeArgs); result = true; } catch (Exception ex) { result = false; } return result; } /** * writes the XML-serialized object to the given Writer. * * @param writer the Writer * @param toSerialize the object to write * @return true if everything goes ok * @throws Exception if something goes wrong */ public static boolean write(Writer writer, Object toSerialize) throws Exception { Class<?> xstreamClass; java.lang.reflect.Constructor<?> constructor; Object xstream; Class<?>[] serializeArgsClasses = new Class[2]; Object[] serializeArgs = new Object[2]; java.lang.reflect.Method methodSerialize; boolean result = false; xstreamClass = Class.forName("com.thoughtworks.xstream.XStream"); constructor = xstreamClass.getConstructor(); xstream = constructor.newInstance(); serializeArgsClasses[0] = Object.class; serializeArgsClasses[1] = Writer.class; serializeArgs[0] = toSerialize; serializeArgs[1] = writer; methodSerialize = xstreamClass.getMethod("toXML", serializeArgsClasses); // execute it try { methodSerialize.invoke(xstream, serializeArgs); result = true; } catch (Exception ex) { result = false; } return result; } /** * reads the XML-serialized object from the given file * * @param filename the file to deserialize the object from * @return the deserialized object * @throws Exception if something goes wrong while reading from the file */ public static Object read(String filename) throws Exception { return read(new File(filename)); } /** * reads the XML-serialized object from the given file * * @param file the file to deserialize the object from * @return the deserialized object * @throws Exception if something goes wrong while reading from the file */ public static Object read(File file) throws Exception { return read(new BufferedInputStream(new FileInputStream(file))); } /** * reads the XML-serialized object from the given input stream * * @param stream the input stream * @return the deserialized object * @throws Exception if something goes wrong while reading from stream */ public static Object read(InputStream stream) throws Exception { Class<?> xstreamClass; java.lang.reflect.Constructor<?> constructor; Object xstream; Class<?>[] deSerializeArgsClasses = new Class[1]; Object[] deSerializeArgs = new Object[1]; java.lang.reflect.Method methodDeSerialize; Object result; xstreamClass = Class.forName("com.thoughtworks.xstream.XStream"); constructor = xstreamClass.getConstructor(); xstream = constructor.newInstance(); deSerializeArgsClasses[0] = InputStream.class; deSerializeArgs[0] = stream; methodDeSerialize = xstreamClass.getMethod("fromXML", deSerializeArgsClasses); // execute it try { result = methodDeSerialize.invoke(xstream, deSerializeArgs); } catch (Exception ex) { ex.printStackTrace(); result = null; } return result; } /** * reads the XML-serialized object from the given Reader * * @param r the reader * @return the deserialized object * @throws Exception if something goes wrong while reading from stream */ public static Object read(Reader r) throws Exception { Class<?> xstreamClass; java.lang.reflect.Constructor<?> constructor; Object xstream; Class<?>[] deSerializeArgsClasses = new Class[1]; Object[] deSerializeArgs = new Object[1]; java.lang.reflect.Method methodDeSerialize; Object result; xstreamClass = Class.forName("com.thoughtworks.xstream.XStream"); constructor = xstreamClass.getConstructor(); xstream = constructor.newInstance(); deSerializeArgsClasses[0] = Reader.class; deSerializeArgs[0] = r; methodDeSerialize = xstreamClass.getMethod("fromXML", deSerializeArgsClasses); // execute it try { result = methodDeSerialize.invoke(xstream, deSerializeArgs); } catch (Exception ex) { ex.printStackTrace(); result = null; } return result; } /** * Deserializes an object from the supplied XML string * * @param xmlString the XML to deserialize from * @return the deserialized object * @throws Exception if something goes wrong */ public static Object deSerialize(String xmlString) throws Exception { Class<?> xstreamClass; java.lang.reflect.Constructor<?> constructor; Object xstream; Class<?>[] deSerializeArgsClasses = new Class[1]; Object[] deSerializeArgs = new Object[1]; java.lang.reflect.Method methodDeSerialize; Object result; xstreamClass = Class.forName("com.thoughtworks.xstream.XStream"); constructor = xstreamClass.getConstructor(); xstream = constructor.newInstance(); deSerializeArgsClasses[0] = String.class; deSerializeArgs[0] = xmlString; methodDeSerialize = xstreamClass.getMethod("fromXML", deSerializeArgsClasses); // execute it try { result = methodDeSerialize.invoke(xstream, deSerializeArgs); } catch (Exception ex) { ex.printStackTrace(); result = null; } return result; } /** * Returns the revision string. * * @return the revision */ @Override public String getRevision() { return RevisionUtils.extract("$Revision$"); } }